Examples of electronically controlled cartridge control valves for fuel injectors are shown in U.S. Pat. No. 5,494,219 to Maley et al., U.S. Pat. No. 5,407,131 to Maley et al., U.S. Pat. No. 4,869,462 to Logie et al., and U.S. Pat. No. 4,717,118 to Potter. In each of these examples, the injector includes a mechanically actuated fuel pumping plunger and an electronically actuated fuel pressure control valve assembly. The pressure control valve assembly includes a solenoid operated poppet valve member that controls fuel pressure in the injector in order to control fuel injection delivery and timing. Fuel pressure is controllably enabled to be developed within the injector by electrical actuation of the pressure control valve assembly. Fuel pressure is controllably prevented from developing within the injector by not electrically actuating the pressure control valve so that fuel can spill through a return passage while the plunger is undergoing a portion of its downward pumping stroke.
In such electronically controlled fuel injectors, the armature of the pressure control valve assembly moves the poppet valve member in one direction until it engages a valve seat, and holds the poppet valve in its closed position to enable fuel pressure to be developed in the injector, eventually resulting in fuel injection. At the end of the fuel injection cycle, the solenoid is de-energized, and a return spring moves the poppet valve member off the valve seat, returning the poppet valve member to its open position, which prevents the development of fuel pressure by spilling the fuel back to a fuel reservoir.
Engineers are often looking for ways to improve the performance and reliability of control valves. Performance can be improved by shortening the response time of the valve. A shortening of the response time can be accomplished both by improving the speed at which force develops within the solenoid and by increasing the magnitude of the force produced by the solenoid. However, space constraints and other factors known in the art often prevent the use of larger solenoids, and the use of exotic materials to hasten the build up of force in the solenoid is often prohibitively expensive. Reliability in a control valve can be improved by decreasing the number of electrical connections existing between an external terminal and the wire winding of the solenoid. By decreasing the number of connections, robustness of the valve can be improved. Furthermore, a reduction in electrical joints is often accompanied by a corresponding decrease in the number of parts required to assemble the control valve. Generally, an over all decrease in the part count for a particular control valve is desirable both from a manufacturing and cost view point. Finally, there is usually room to improve the manufacturability of a control valve by both decreasing the part count and simplifying the assemblage of the remaining components.
The present invention is directed to improving control valves.